This invention relates to a fluidized bed reactor for burning material containing incombustible matter in a continuously effective manner.
During operation of a fluidized bed reactor large particles usually accumulate in the lower part of the reactor and have to be continually or periodically removed. In spite of the fact that fine particles are entrained by the gas flowing through the reactor, in particular when the fluidized bed reactor is operating at high superficial gas velocities, the material withdrawn from the bottom part contains fine particles. Usually, it also contains combustible matter. The fine particles as well as the combustible material should be returned to the reactor to be utilized there.
An attempt to solve this problem has been made, as described in U.S. Pat. No. 3,397,657, by separating fine particles from the coarse particles of the discharged material by means of pressurized air in an air pipe located exteriorly of the reactor. However, the system has been found to have technological disadvantages, such as low separation rate of fine particles.